Tractors used in construction and agricultural applications have power plants such as hydraulic pumps driven by the tractor engine. Typically, hydraulic reservoirs also reside on the tractor. A hydraulic line from the pump on the tractor is connected to a directional control valve. A return line from the directional control valve goes back to the reservoir. The directional control valve has two outputs with hydraulic lines attached thereto. Each of the hydraulic lines has a coupling affixed thereto which mates with a reciprocal coupling half on lines from an implement which is driven by the tractor's pump. In other words, couplings are used to connect and disconnect hydraulic lines which run the implement.
When the implement is disconnected from the tractor two potential problems are created. First, hydraulic fluid in the supply, return or the supply and return lines downstream of the directional control valve may be hydraulically locked which makes coupling of those lines to the coupling halves of the implement difficult if not impossible. Second, ambient heat from the air and radiant heat from the sun cause the fluid in the disconnected driven piece of equipment (implement) and its connecting hydraulic lines to increase in temperature and pressure thus making it difficult to connect the hydraulic pressure source to the hydraulic load (driven equipment). Usually the implement has two couplings, one for the power line supplying the load and the other for the return line which sends the fluid back to the directional control valve. Increased temperature and pressure of the fluid in the couplings and the hydraulic lines to the load make the couplings difficult to reconnect upon subsequent operation of the implement.
U.S. Pat. No. 2,675,829 to Livers discloses a quick-disconnect coupling with a selectively operable valve.
U.S. Pat. No. 4,881,573 to Durant illustrates a coupler having two poppet valves. The first poppet engages a ball check valve formed in the male coupling and the second poppet is actuated by a manually operated cam. A passageway exists in the piston to allow fluid to be vented or to pressurize the female valve.
U.S. Pat. No. 4,598,896 to Maldavs illustrates a coupler having a spool and a port within the spool. An annular seal is fixedly positioned about the port in the spool. The spool is slidable with respect to the seal which enables pressure to be relieved in the female during coupling and uncoupling with the male.
U.S. Pat. No. 4,303,098 to Shindelar discloses a coupler having a female half which includes a female valve having an elongated stem for engaging the male half. The female half of the coupling is vented by a pivotable cam which moves the inner member of the female half to release its locking means and then opens a poppet valve to open the outlet port.
U.S. Pat. No. 4,249,572 to Shindelar et al. discloses a female half which is self-relieving. The female half includes dual poppet valves which are linked together. One of the poppet valves vents the female half of the coupling when the male and female valves are disengaged and uncoupled.
U.S. Pat. No. 4,181,150 to Maldavs recites that quick disconnect couplings are frequently used on agricultural implements to connect hydraulic hoses for conveying pressurized hydraulic fluid. The Maldavs '150 patent goes on to state that agricultural tractors have hydraulic systems which are connected to agricultural implements.
Maldavs' '150 patent discloses a lever-type quick disconnect female coupling for co-action with a check valve equipped male coupling. A movable valve member actuated by the lever functions as a sealing valve for the female coupling and as a push member for opening the check valve of the male coupling. Maldavs' '150 patent recites that lever-type quick disconnects were developed to overcome the problem of connecting or disconnecting coupler halves under pressure. However, according to the Maldavs '150 patent, lever-type couplings are no panacea because they can interfere with the flow of fluid through the coupling and experience other problems.
U.S. Pat. No. 4,347,870 was issued to Maldavs and discloses a quick disconnect female coupling with a lever-operated valve. The lever operates a cam inside the coupling which pulls open the valve assembly of the female coupling and pushes a plunger which opens the valve of a male coupling which is connected to the female coupling. The cam is positioned within a large flow passage in the female coupling.
U.S. Pat. No. 6,016,835 to Maldavs discloses an inner valve spool having an end which is engageable by a lever-operated cam to move the inner valve spool relative to the outer spool and allow fluid in the female housing to flow out through ports and be relieved.
U.S. Pat. No. 3,710,823 to Vik discloses two hydraulic couplers operable by a cam actuator. Couplers are affixed to a mounting bracket which in turn is affixed to a tractor. The couplers use a cam actuator which move coupler portions to a position wherein the fluid flow through the couplers is shut off while the coupler parts remain mechanically connected. The coupler members move internally to permit connection of the coupler halves under pressure.
U.S. Pat. No. 4,009,729 to Vik discloses a hydraulic coupler having an intermediate valve which permits closing off flow from the inlet end to the outlet end. The valve is actuated by a handle affixed to a cam. The cam also actuates a piston which moves to enlarge a chamber which relieves pressure in the chamber to permit connection of the coupling halves under pressure.
U.S. Pat. No. 4,373,551 to Shindelar discloses a lever-actuatable cam which can vent two female coupling halves. The cam actuates valves located in the end of the female coupling halves.
U.S. Pat. No. 5,918,633 to Zeiber discloses a female coupling which resides in a housing and which includes an inner body. Movement of the inner body of the female portion moves the relief valve positioning member axially away from the male member opening the relief valve and venting the female member through the housing.
U.S. Pat. No. 6,095,190 to Wilcox et al. discloses a female half having a main valve, a relief valve and a sliding sleeve valve. The relief valve is designed to reduce pressure behind the main valve so as to permit easy coupling under pressure when the female half is under pressure. Pressure relief is accomplished within the couplings.
U.S. Pat. No. 6,116,277 to Wilcox et. al discloses a coupling useable on farm implements having a metal to metal vent valve in the female half of the coupling. The female half of the coupling is vented when the female half is disconnected or partially disconnected from the male half. When the male half is being coupled with the female half the female half is vented thus making coupling easy.
There is a need for a tractor mounted manifold which can vent the hydraulic lines between the directional control valve and the manifold enabling connection of coupling halves mounted on the manifold to coupling halves mounted on the hydraulic lines of the implement.
There is a need for an implement mounted ventable manifold having coupling halves affixed thereto. The implement and the manifold attached thereto maybe separated from the tractor which supplies the hydraulic power to the manifold and the implement. There is a need to vent the manifold so as to enable easy recoupling of the hydraulic lines from the power source to the couplings on the implement mounted manifold.
Alternatively, there is a need for two ventable manifolds each having coupling halves affixed thereto, one manifold being mounted on a tractor and one manifold being mounted on an implement. In this way the hydraulic supply and return lines of the implement and the tractor may be vented.